Wood chipper



I Get. 3,}939. F. PELOT ET AL I 2,174,593

WOOD GHIPPER Filed Oct. 2'7, 195? XNVENTORS Fran/r P6206 anal- ATTORNEYSZ Patented :1.3, 1939 PATENT OFFICE 2,114.59: woon cmrraa Frank Pelot,Port Edwards, and Richard Gots, Nekocca, Wia, assigncrs to CarthageMachine Company, York N. Y., a corporation of New Application October27, 1937, Serial No. 171,220

1 Claim.

The present invention relates to certain new and useful improvements inwood chipping machines of the type commercially used for the purpose ofcutting wood into chips of the proper kind preparatory to making pulptherefrom for use in the manufacture of paper, paper board and the like.Wood chipping machines of this general kind may be said to compriseessentially arotatable disc carrying one or more cutting knives locatedin radial slots therein so that the chips cut may pass through the discwhere they are taken care of, a feeding spout or trough arranged in asuitably inclined position and adapted to bring the wood into contactwith the rotatable disc so that the knives may act upon the wood, and astationary bed knife arranged in a horizontal position so that it maycoact with the knife or knives of the rotatable disc to cut off or shearthe chips from the wood. In order to obtain the best results it is quitenecessary that the stationary bed knife should be kept sharpandeffective at all times.

The stationary bed knife therefore provides a cutting edge against whichthe disc knives can shear off the ends of sticks fed down toward them atthe angle of the chute or spout. When the knife is passing through theupper part of a stick the lower fibers of the wood act as bed knives forthe upper ones, but when it comes to the last or bottommost fibers agood sharp edge on the bed knife is necessary or the fibers will benddown and peel ofi without being cut. These peelings or slivers will notcook satisfactorily in the digester and are very difficult to break upinto usable chips. It is therefore necessary to keep the bed knife sharpand hence an easy means of removing it f0r grinding is necessary withwhicha horizontal adjustment seems to be the most feasible plan.Therefore it is customary to have a successful bed knife bevelled on itsupper front edge where it is associated with the lower end of the feedspout so that said bevelled part may serve as a continuation of thefeeding spout in order that the end of the wood may be kept at all timesvery close to the cutting knives.

But even with this bevelled upper front edge on the bed knife althoughquite successful results l are obtained if the feed spout is square incrosssection yet when the feed spout is round as is quite often the caseserious diiiiculties arise in forming the cutting action because of thelimited area of .the bevelled edge of the bed knife where it serves as acontinuation of the round inner surface of the spout and it is theobject of our surface of the bed knife and on the vertical surface, thecurvature of the arc thereof coinciding with the curvature of the innerwall of the spout in a manner to be hereinafter more fully explained.

The principal object of our invention is therefore to provide a cuttingtool of such construction that it will at all times and during theentire process of cutting afford a cutting edge of perfect coincidencewith the feed spout and providing therewith a feed spout particularly around one having a continuation surface within itself and along thebevelled curved outline of the bed plate so that it will extend intodirect contact with the cutting tool and knives. Obviouslyaportion ofthe bed plate or cutting tool will serve as a wear member in addition tothe performance of its other function of a sharp bed knife.

The invention therefore may be said to consist essentially in theconstruction, combinatipn and arrangement of the various parts and innumerous details and peculiarities thereof substantially as will appearfrom the following detailed description of the construction and usewhich is to be considered in conjunction with the accompanying drawingand will hereinafter be definitely pointed out in the claim.

In the drawing illustrating our invention:

Fig. 1 is a view in elevation of our improved wood chipping machine,certain parts being broken away or represented conventionally tosimplify the illustration;

Fig. 2 is a longitudinal vertical section of the same;

Fig. 3 is a perspective detail view of the feed spout viewed from apoint looking into the same through the elliptical lower end;

Fig. 4 is a frontfperspective view of the bed plate in invertedposition;

Fig. 5 is a cross section of the same on the line 55 of Fig. 4;

Fig. 6 is an edge view of the bed plate in its normal horizontalposition.

Like characters of reference designate like parts throughout all thefigures of the drawing.

The rotatable disc I is mounted on a shaft 2,

which is driven by any suitable source of power not shown. This disc Iis-provided with one or more slots of suitable size and shape which arein a substantially radial location and near each slot is mounted a knife3, which as shown in Fig. 2 has the proper position to enable it toexert an effective cutting action upon the wood presented thereto by thespout or chute 6 which is located contiguous to the disc and supportedon the main frame. The knife 3 as shown in the drawing projects outslightly from the surface of the disc I, and the distance between thecutting edge of the knife and the disc I, determines the thickness ofthe chips or cuttings produced. A casing 4 is preferably used to enclosethe upper portion of the disc I, while the lower portion of the discextends downwardly into a suitable space formed by the main frame or theconstruction walls of the apparatus. The feeding spout 6 is located inany desired position but usually it is found preferable to locate iteccentric with respect to the shaft 2 and inc-lined at an angle to thehorizontal plane through said axis and arranged to project through thecasing 4 into close proximity to the disc I as shown in Fig. 2. Theparticular spout illustrated in the drawing is circular and while it isobvious that spouts of square or rectilinear or other suitable crosssection may be employed, it will be understood that our presentinvention which applies more particularly to a bed plate having a curvedoutout portion is intended chiefly for use with a circular spout.

Our improved stationary bed knife 1, is supported at substantially rightangles to the disc I, by suitable means consisting of a portion of theframe or the sub-structure of the walls of the machine. Stationary bedknife I preferably comprises a single piece of tool steel ground so thatit has what may be termed an obtuse tool angle which, if furtherdescription be needed, is one in which the tangent of the angle betweenthe lower active face of the tool as shown at the bottom in Fig. or atthe right hand edge in Fig. 2 and the disc I is say, that is to say,good results may be expected to be obtained by using a tool having aclearance angle of 1:16 for example. As already stated the upper activeface of the tool or knife I which is shown in front in Fig. 4 and at theright in Fig. 5 and at the top in Fig. 2, is ground with a bevel in itscentral portion so that when the tool is placed in the chipping machineas it is shown in Fig. 2 this bevel portion forms a substantiallycontinuous extension of the inner face of the feeding spout, all as isclearly shown in Fig. 2.

The bed knife I is adapted to be advanced or retracted with relation tothe rotary disc I, and its knife or knives 3, by means of adjustingscrews I II, which have a round end so that they may have a ball andslot connection with the knife I by having the said ball shaped endsenter the round ended slots 8, 8 in the rear and thinner portion of thesaid bed knife. Further the said screws after being adjusted and therebyadjusting the position of the cutting tool I so that the sharp edgethereof may be properly related to the cutting edge of the knife 3, maybe fixed in any desired position by means of the clamping screw I2 whichpasses through a slot II in the cutting tool I and employs appropriateblocks above and below the thinner rear portion of the cutting tool 1 soas to hold the tool tightly in its adjusted position by merely turningthe hand wheel I2 so as to loosen or tighten the same.

It has already been suggested that peculiar difliculties arise in theuse of a circular spout and that it is the chief object of our presentinvention to overcome such difficulties. It will be noted that at thepoint where the cylindrical surface of the spout intersects the planepassing through the sloping surface at the upper front edge of the bedknife I, there can be only one line which must be just at about themiddle, where the slopes of the two surfaces, that is the surface on theinside wall of the spout and the surface on the bevel of the upper edgeof the bed knife, are perfectly lined up with each other although theyare parallel, unless something is done to cure this objection which weseek to obtain by the use of our improved cutout section in the bedknife. Obviously a horizontal plane passing through the top surface ofthe bed knife when it is in its normal position as shown in Fig. 2, orin Fig. 3 will cut the elliptical opening of the spout that faces therotary disc I at a point on each side. This is clearly shown in Fig. 3.From these intersecting points to the line along which the cylindricalsurface of the spout coincides with the plane of the sloped section ofthe bed knife face the spout obviously overhangs the bed knife. This weavoid by cutting an arc in the top of the bed knife at 9, and anotherare in the front face of the bed knife at I4, between which two arcs thesloping or bevel portion is arranged as shown at 9 and I4 in Fig. 5 andthese curves enable the bevel portion to coincide with the innercylindrical face of the spout 6 at its elliptical end I3 so that thereis a continuation and complete extension which is not confined to justone line and' by this means the overhanging of the bed knife is avoidedand rectified.

The nearer towards the sides of the spout that Q a stick of wood may liewithin the same, the more its last fibers to be cut must bend down overthis overhanging portion of the spout before they are cut by the bedknife. This intensifies the wear on the spout at the sides and causes itto be finally considerably steeper at the bottom than at the top. Thestick then is supported only at the top until the knife hits it andcatapults the top part up using the corner where the wear starts as afulcrum. This bouncing makes uneven lengths of chips and slivers anddecreases the capacity of the machine by slowing down the feed.

When however, the bed knife has the curved bevel section the cylindricalsurface of the spout is carried right down to the cutting edge, which asdescribed is in the shape of an arc of an ellipse on the vertical face.The sticks do not need to bend down to get out. The wear on the spoutsurface is reduced and the logs therein feed better. And it is alsodetermined as another result of the use of the curved bevel section thatthe bed knife may be made much thicker than has been the practiceheretofore. The intersection of the horizontal plane through the top ofthe surface of a bed knife 2 or 3 inches thick with the ellipticalopening in the spout comes down so low that the two points ofintersection are not as near to the sides of the. spout as they shouldbe; but if the bed knife is made substantially thicker, say 6 inchesthick or more, then the points of intersection would be much fartherapart and the cutting edge would then be able to cover substantially thewhole of the elliptical opening of the spout which is a decided and verymaterial advantage in obtaining the best results.

We find it very desirable to cover the curved surface with some hardmaterial like stellite and also the vertical surface of the knife acrossso that the sharp edge may last much longer after being ground. Thishard material can be re.- placed by welding after it has been all groundoff. The feature is of importance and we lay special stress thereon.

It will be understood that the sizes and pro-- portions of the variousparts and their exact relative arrangement with reference to each othermay be varied to a wide degree without depart-' ing from the principleof the invention which is not confined to the particular improvementshown and described. The curved bevel portions may vary in size withinwide limits and the angle of' the bevel from the upper face to the sideface of the bed knife may be changed to accommodate the best results andthe invention is intended to include such other improvements as may fallwithin the scope of the appended claim.

What we claim is:

In a wood chipper of the class described, a feed spout curved in crosssection, an adjustable stationary cutting knife, having its upper andlower surfaces in parallel planes-at, the bottom of the outlet end ofthe feed spout, and a knife rotatable in a plane substantially at rightangles to the stationary knife, said stationary knife having the planeof its upper surface intersecting the curved lower end portion of thespout and having a concaved cut-out at theupper forward edge thereofconforming to and coinciding with the inner curvature of the innersurface of the lower end por-

